Tune after Fuel Pump Install?

[maximos]

I recently installed a 255lph fuel pump in my car and my gas mileage has dropped tremendously. I used about 11 gallons to go 170 miles when prior to the swap I could make the trip in about 6 gallons. Will I need to retune my car to make everything run normally? Thanks in advance.

 

[final5-0]

Makes me wonder if you run an afpr and since the larger pump install

It might be turned up too high

Grady

 

[drakesdad]

make sure the tank isn't leaking......

 

[Stanger007]

lol.

Make sure your fuel pressure is still where it was before (39psi stock w/ no vacuum). No tune needed on any cars I've worked with using the 255s.

Wes

 

[HISSIN50]

I agree with the wise gents here.

I'm surprised that you havent gotten a lean-limit code if it is pressure related (I was thinking that the return line might have gotten squished, but then lambda readings should have gone off the chart).

As said, check that ol' pressure out.

Good luck.

 

[maximos]

I know there isn't a tank leak because I just had a new tank installed as well...Long story about the old one. So you're saying I should take it back to the shop and have them work it out?

 

[HISSIN50]

I know there isn't a tank leak because I just had a new tank installed as well...Long story about the old one. So you're saying I should take it back to the shop and have them work it out?

If a shop did the tank and pump, I would have them look at it. It sounded like you had a shop do the tank but you did the pump. If so, I would atleast check pressure before taking it down there. If pressure is within spec, that would leave a tank install issue or leak (though you noted none).

 

[drakesdad]

Rob from Lasota racing is in your area......if you can't find the gremlins he is def. worth the price of the fix........but follow the above advice is you have ruled the leak out......keep us updated...GL

 

[maximos]

The shop did both the pump and the tank.

 

[fkurls1]

Did you install an adjustable fuel pressure regulator along with the pump?

 

[milewsky80]

you were getting damn near 30mpg??!!

 

[HGFireHazard]

There is some solid information listed above. Since you don't have a stock longblock it's probably a good idea to have an AFPR if you don't already. I don't see the need for one specifically for adding a higher flowing fuel pump as that's what I did as have many others.

Our fuel system is a return style, the pump puts out the fuel and whatever isn't used is returned to the tank.

Certainly 15 mpg is low for your combo, but getting 28ish before with an H/C/I? Have you tuned your car before? That kind of mileage seems like your A/F ratio might have been a little lean? Maybe you just did a real good job of keeping your foot out of it and shifting at a nice RPM.

Just like others have said, check your fuel pressure, check your regulator, check for codes, and if all those seem normal take it back to the shop and have them sort it out.

 

[final5-0]

you were getting damn near 30mpg??!!

Somebody give this man a Ceee Garrr

He is the kind of guy that is observant

I went back and looked at the original post

The complaint was based upon 170 miles traveled

Actually ... it was worded ... "to go 170 miles"
then
The word ... "trip" ... was used

So we got ............

170 miles divided by 11 gal = 15.45 mpg
and
170 miles divided by 6 gal = 28.33 mpg

More clarification of the driving conditions could be helpful here

I mean ... If the 170 miles were all in town miles with some spirited driving
conditions ... you would expect less than optimum

Then again ... over 28 mpg

Even if they were all highway miles ....
thats pretty dad gum good in my book

Grady

 

[scorpion95]

I'm getting about 27mpg hwy now with my 95 with 152k on the clock. 28mpg hwy is attainable but you'd have to travel around 65mph for quite a long way without slowing down for traffic, etc. During the summer months on my 400 mile trip to upstate NY I can easily go 330-335 miles to a tank before I have to fill up. It usually takes 12-12.5 gal to fill up. I have found that I get the best mileage with Valero's 93 octane.

To the OP sorry I can't help you more than what the other gents have mentioned. Just for laughs what is your timing set at? What octane gas are you running?

 

[GTA_V6_Mustang]

On the highway road trips I tend to take in my car I can squeaze 28mpg out of the old 302. I dont think the fuel pump is the issue for the OP but check the return lines and make sure they are not crushed.

BTW 28mpg seems to be common highway for high mileage 302's. City however I pull a consistent 19-20mpg.